Because your home's foundations are the closest part of the house to the ground, they're also one of the most common entry spots for bugs. By keeping foundations clear and protected, you can greatly reduce the likelihood of infestation.
Insects such as termites, ants, fleas and spiders are particularly good at breeding and thriving in wet areas. By keeping moisture away from your foundations, you can make it more difficult for them to reproduce. Keep piles of wood, leaves, mulch or grass clippings away from foundations, and place firewood far away from the house to avoid tempting termites [source: Amundsen].
Check for gaps along the foundation and siding joints as well. Often, the bottom row of siding or trim is not securely sealed to the home and provides a gateway for insects. Check up under this row for gaps or poor connections, and use trim, caulk or foam to fill this space [source: Gouge et al].
Many homeowners choose to use chemical insecticides or termicides to treat their foundations, and these treatments are often unavoidable. For a more natural solution, consider placing boric acid or diatomaceous Earth at the base of these walls. These substances are non-toxic and will not harm pets or family members [source: Garrett].